Differential Diagnosis for Foot Infection with Initial Abscess Followed by Sloughing Skin

Critical Red Flags Requiring Immediate Assessment

The presence of crepitus on examination or tissue gas on imaging is a critical red flag for necrotizing fasciitis or other limb-threatening infections, as recommended by the Infectious Diseases Society of America 1
Extensive ecchymoses or petechiae are indicative of severe infection and require immediate attention, according to the Clinical Infectious Diseases guidelines 1
Bullae, especially hemorrhagic ones, are a sign of severe infection and necessitate urgent evaluation, as stated in the Clinical Infectious Diseases journal 1
Pain out of proportion to clinical findings is a red flag for necrotizing fasciitis, as highlighted by the Infectious Diseases Society of America 1
New onset wound anesthesia is a critical sign of nerve damage and requires immediate assessment, as recommended by the Clinical Infectious Diseases guidelines 1
Rapid progression of infection is a sign of severe infection and necessitates urgent attention, according to the Clinical Infectious Diseases journal 1
Extensive necrosis or gangrene is a critical sign of severe infection and requires immediate evaluation, as stated by the Infectious Diseases Society of America 1

Necrotizing fasciitis requires urgent surgical consultation and intervention, as recommended by the Infectious Diseases Society of America and the American College of Surgeons 1, 2
Severe diabetic foot infection with deep tissue involvement is a moderate-to-severe infection that requires prompt treatment, according to the International Working Group on the Diabetic Foot and the Infectious Diseases Society of America 4, 5

Evaluate the patient at three levels: as a whole, the affected limb, and the infected wound, as recommended by the International Working Group on the Diabetic Foot and the European Society of Cardiology 4, 9
Perform a probe-to-bone test to assess for osteomyelitis, as stated by the International Working Group on the Diabetic Foot 4
Measure the extent of cellulitis and document the presence of purulent discharge, necrotic tissue, and foul odor, as recommended by the International Working Group on the Diabetic Foot and the European Society of Cardiology 4, 10
Obtain plain X-rays immediately to detect gas in tissues, foreign bodies, and bone involvement, as recommended by the American College of Radiology and the European Society of Radiology 5, 10
Consider urgent CT scan to detect deep soft-tissue abscesses, sinus tracts, and extent of tissue involvement, as stated by the American College of Radiology and the European Society of Radiology 9, 10

Polymicrobial infections are the most common cause of necrotizing fasciitis, as highlighted by the Infectious Diseases Society of America 1
Group A Streptococcus is a common cause of monomicrobial necrotizing fasciitis, as stated by the Infectious Diseases Society of America 1
Clostridium species are a common cause of gas gangrene, as recommended by the Infectious Diseases Society of America 1
Staphylococcus aureus, including MRSA, is a common cause of severe diabetic foot infections, as highlighted by the Infectious Diseases Society of America and the International Working Group on the Diabetic Foot 6, 8

Determine the urgency of the situation within minutes, as recommended by the Infectious Diseases Society of America and the American College of Surgeons 1, 2
Provide immediate surgical consultation and empiric broad-spectrum IV antibiotics if necrotizing infection is suspected, as stated by the Infectious Diseases Society of America and the American College of Surgeons 1, 2
Use broad-spectrum coverage for severe or limb-threatening infections, including MRSA, gram-negatives, and anaerobes, as recommended by the Infectious Diseases Society of America and the International Working Group on the Diabetic Foot 2, 7